I recently purchased a 1985 vt 750 under the understanding that the engine had been rebuilt due to valve noise. I was told that the wiring had issues which I was confident I could fix. I hooked a battery up and the engine would roll over if I shorted the solenoid. I found a blown ignition fuse and consequently a shorted wire. Replaced the wire and got spark and the engine rolls using the starter button. I put gas in the tank and rolled the engine. I got misfire thru the carbs and nothing else. I did a compression check and have 0 on both cylinders. I dont see any way to check the timing chains without removing the engine. what is my best course of action. Thanks in advance for any advice. Rick
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1985 vt 750 no compresion
- Thread starter vt750
- Start date
Is your gauge working? Easiest things first, checking with compressed air is the easiest. If the gauge is working, Brian P is a good guy to listen to.
If you can borrow a leakdown tester, you can pressurize each cylinder and listen to find where all the air is going.
Note to self, always check engines rebuilt by others very carefully prior to connecting power in case they got timing or valve clearances very wrong.
If you can borrow a leakdown tester, you can pressurize each cylinder and listen to find where all the air is going.
Note to self, always check engines rebuilt by others very carefully prior to connecting power in case they got timing or valve clearances very wrong.
TK4
Well-known member
This is a hydraulic valve motor (no adjustment), best go buy a shop manual before going any further.
Assuming it hasn't crashed the valves, it wouldn't make sense to have 0 compression no matter how far off timing was (assuming the cams are actually moving). Obviously if timing is out by much it won't run. Interesting situation, hopefully the OP finds the problem and it is something dumb and easy/cheap to fix.
Obtain service manual. Remove valve covers and whatever crankcase cover is necessary to expose timing marks at crankshaft and camshafts. Check alignment of timing marks.
Timing marks off by a tooth could result in a no-start but it should still have some compression. Timing off by sufficient to bend a valve, will bend a valve ... resulting in no compression. Only way to find out is to verify alignment of timing marks between crank and camshafts.
If the engine was rebuilt due to "valve noise" and it has hydraulic lash adjusters ... that makes one wonder and say "hmmm".
Timing marks off by a tooth could result in a no-start but it should still have some compression. Timing off by sufficient to bend a valve, will bend a valve ... resulting in no compression. Only way to find out is to verify alignment of timing marks between crank and camshafts.
If the engine was rebuilt due to "valve noise" and it has hydraulic lash adjusters ... that makes one wonder and say "hmmm".
Id like to thank everyone for your help.I have checked the timing and it seems to be correct and also i brought piston to tdc and valves all closed. I blew smoke in the cylinder and it came out the intake. I am asuming the valves are bent so I pulled the engine and I will have pull the heads and check. Thanks again for all input, Rick
Thanks for the update. Post pics when you get it apart.
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